Circuit interrupting and reclosing devices function to isolate a fault condition in a power distribution system and upon clearing of the fault condition to reclose the circuit. Faults in a power distribution system can occur for any number of reasons and are typically transient. Detection and isolation of the fault mitigates damage to the system as a result of the fault. Automatic reclosing of the circuit following a fault returns the power distribution system to normal operation quickly and without operator intervention.
Recloser devices may be designed to operate after a fault interruption to reclose the faulted line or lines. Following reclosing, if the fault is not cleared the recloser device will detect the fault and again operate to open and isolate the fault. This process of closing, fault sensing and reopening may occur several times before it is determined that the fault is persistent, i.e., is a fault requiring some reparative intervention, and the recloser locks out to isolate the fault.
The process of reclosing into a fault, however, may have the detrimental effect of repeatedly subjecting the power distribution circuit and any connected loads to the fault current and other potentially damaging current anomalies. Given the close, sense, reopen operating nature of the recloser device, this may occur several times before the fault is cleared or the recloser is locked out.